Plant canopy interception of rainfall and its significance in a banded landscape, arid western New South Wales, Australia

Abstract

Abstract. The canopy interception storage capacity of three plants in an arid, banded (runoff-runon) landscape was determined in the field from weight gain under artificial rain. The plants, two shrubs and a grass, were the bladder saltbush Atriplex vesicaria (Heward ex Benth.), the pearl bluebush Maireana sedifolia (F. Muell.) P. G. Wilson, and perennial Mitchell grass Astrebla lappacea (Lindl.) Domin. For saltbush and Mitchell grass, canopy water storage capacity (1.3 mm) correlated strongly with projected canopy area, while for the dense canopy of the bluebush (2.0 mm capacity), plant weight was a better predictor. In view of canopy cover amounts in each plant community, and the mean rain day rainfall of 5.7 mm, estimated annual water losses amount to 32% for Mitchell grass communities, 5% for saltbush communities, and <1% for bluebush communities. Canopy interception loss is shown to be a significant influence on the water redistribution that supports banded landscapes in the arid Broken Hill area.

Modelling Wetland Growing Season Rainfall Interception Losses Based on Maximum Canopy Storage Measurements

“…In one study conducted in Texas, the interception losses for Curlymesquite grass were estimated as 10.8% of annual rainfall, while interception losses for Sideoats grama grass were estimated at 18.1% of annual rainfall [21]. In another study conducted in Australia, higher values were observed for Curly Mitchell grass at 32% of annual rainfall [31]. The study area in [21] has a mean annual precipitation of 609 mm, while, in [31], it is 255 mm.…”

“…In another study conducted in Australia, higher values were observed for Curly Mitchell grass at 32% of annual rainfall [31]. The study area in [21] has a mean annual precipitation of 609 mm, while, in [31], it is 255 mm. In our study for interception losses values of wetland plants, this area has a mean annual precipitation of 552 mm and lies between values of the two previously mentioned studies.…”

“…The first is that interception losses from forest are generally greater in absolute volume than those from lower vegetation. However, some studies [31] showed that interception of grasslands can reach approximately 30% of annual rainfall, which is similar to many forests [34]. The second reason is the difficulties in measuring rainfall interception in lower vegetation, especially in natural heterogeneous ecosystems.…”

“…I max is calculated as the difference between the freshly collected and the weight of a soaked plant. There are two methods of soaking plants with water: spraying [21,31,32,44] and submerging [1,19,45]. In this study, plants were submerged because it is less ideal with spraying where the droplet size will cause variations [46].…”

“…The number of studies on rainfall interception by lower vegetation are inadequate with focuses mainly on: grasslands [19,21,31], drylands [1,20] shrublands [31,32], or croplands [33]. There are two reasons for this.…”